Flow responsive switch means



March 17, 1970 H. D. HUTCHINSON ET AL v 3,501,605

FLOW RESPONSIVE SWITCH MEANS Filed June 26, 1968 '0 Ill/III/III/INVENTORS HAROLD D. HUTCHINSON WILLIAM C. GREGGE BY I F|G. 4 Z/Joifa Q42a A7701? EYS United States Patent Office 3,501,605 Patented Mar. 17,1970 3,501,605 FLOW RESPONSIVE SWITCH MEANS Harold D. Hutchinson andWilliam C. Gregge, both of 903 Colorado Ave., Santa Monica, Calif. 90404Filed June 26, 1968, Ser. No. 740,162 Int. Cl. H01h 35/40 US. Cl.20081.9 6 Claims ABSTRACT OF THE DISCLOSURE A switch housing includingan enclosure is provided for insertion in a fluid line such that if thefluid flow through the enclosure drops below or rises above apredetermined flow rate, the switch in the housing will be actuated.This actuation is accomplished by an arm passing from the interior tothe exterior of the enclosure through a bore in a wall portion of theenclosure which arm will transfer motion imparted to the inner portionof the arm by fluid flow to the outer portion of the arm by a rockingmovement. The outer portion of the arm upon being rocked as a result ofa change in fluid flow rate actuates the switch. The portion of the armpasslng through the bore in the wall is surrounded by an annularresilient material to provide a fluid tight seal and yet permit therocking movement. Further, a rigid transverse pin passes through theresilient material and arm portion in a direction at right angles to theaxis of the bore and the direction of fluid flow, the ends of the pinextending beyond the resilient material to engage opposite interior wallportions of the bore in such a manner as to be blocked againsttranslatory movement in a direction towards the exterior of theenclosure. The pin thus defines a pivot axis for the rocking movementand also prevents the resilient sealing material from being blown outwhen the fluid pressure in the enclosure exceeds the exterior pressure.

This invention relates generally to flow responsive switches and moreparticularly to an improved switch means for insertion in a fluid flowline wherein the switch is actuated whenever the fluid flow rate dropsbelow or rises above a predetermined flow rate.

BACKGROUND OF THE INVENTION In our United States Patent 3,345,478 thereis disclosed and claimed a flow responsive switch for providing anindication of a change in flow rate in a fluid line. As described inthis patent, the structure also functions to actuate a switch wheneverthe fluid flow rate drops below a given value. For example, in a liquidcooling line, should the flow rate of coolant drop below a given valueoverheating of a piece of equipment may result. In such instance, use ofa flow responsive switch connected to deenergize the equipment inquestion should the flow of cooling fluid drop below a given rate wouldbe very advantageous.

The flow responsive switch of our above-noted patent incorporates aunique orifice means wherein orifices of different sizes may bepositioned to intercept the fluid flow and result in a pre suredifferential constituting a function of the flow rate. This pressuredifferential causes movement of a diaphragm which movement in turn istransmitted to the exterior of the flow system to actuate the switch inquestion. A particularly important feature of the invention of thispatent resides in utilizing a rocking arm structure passing through awall of the enclosure incorporating the orifice, there being provided anannular resilient seal ofiering very little resistance to this rockingmovement. Thus the transference of the motion of the diaphragm to theexterior of the structure can be accomplished with very little frictionto the end that accuracy results.

The structure as described above has proved extremely effective and hasconstituted a great advance in the art for flow responsive switchesparticularly wherein the flow rate is small; for example, five gallonsper minute or less. There are many situations, however, where fairlylarge flow rates; for example, up to thirty-two gallons per minuterequire proper monitoring. In these instances, two major problems havebeen encountered. First, the flow rates involved can oftentimes resultin relatively large pressures within the enclosure which tend to pop outthe the annular seal surrounding the portion of the rocking arm passingthrough the wall of the enclosure. Efforts heretofore to anchor this armin place have resulted in increasing the resistance to rocking movementresulting in inaccuracies. Second, the counterforce spring associatedwith such systems and connected to the exterior portion of the rockingarm to counteract the physical movement taking place within theenclosure has had to be changed to change the counterforce whendifferent flow ranges are involved. This is a consequence of theparticular type of physical movement generated in the enclosure inresponse to flow rates.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present inventioncontemplates an improved flow responsive switch means over that shownand described in our prior patent wherein the foregoing two diflicultiesare overcome.

More particularly, the invention contemplates a fluid enclosure havingan inlet and outlet for insertion in a fluid line. This enclosureincorporates orifice means at the inlet area defining an orifice of a.first given cross-sectional area through which the fluid passes. Meansare provided in the enclosure responsive to a given change in fluid flowrate through the orifice for effecting a given physical movement in theenclosure. In the preferred embodiment, this means takes the form of acircular disc secured to the interior portion of an arm means in aposition with its plane normal to the direction of fluid flow tointercept the fluid flow. The disc has a fixed cross-sectional area andcan cooperate with different orifice means of smaller and largercross-sectional areas that may be inserted in the enclosure. The armitself extends through a wall of the enclosure to the exterior thereofand will rock about the point that it passes through the wall inresponse to movement of the disc by the flow of fluid. The exteriorportion of the arm is positioned to actuate a switch such that shouldthe flow rate drop below a given flow rate, the switch will function to,for example, shut off a piece of equipment. This exterior portion of thearm is subject to a biasing counterforce as by a spring. However, it isnot necessary to replace this spring by springs of other springconstants in order to increase the range of fluid flow monitoring.Actually, it is only necessary to change the orifice size to increasethe range of flow rates detectable by the apparatus the diameter of thedisc on the interior portion of the arm remaining the same. In otherwords, the geometry of the structure is such that a greatly increasedrange of fluid flow rates can be monitored by the flow switch apparatus;for example, from less than five gallons per minute to up to thirty-twogallons per minute.

The present invention further contemplates the provision of a uniquesealing and pivoting means at the area of the wall through which the armpasses to permit rocking movement of the arm with very little friction.This sealing and pivoting means includes an annular resilient materialfilling the annulus defined between the exterior portion of the armpassing through the inner wall and the bore in the inner wall receivingthe arm. This annular resilient material provides a tight seal and yetpermits rocking movement in a manner similar to the sealing structuredescribed in our heretofore mentioned United States patent. However, thestructure further includes a rigid transverse pin passing through theresilient material and portion of the arm in a direction at right anglesto the axis of the bore in the wall and the direction of fluid flow. Theends of this pin extend beyond the resilient material to underlieopposite interior wall portions of the bore in such a manner that thepin is blocked against translatory movement toward the exterior.

With the foregoing arrangement, extremely high pressures as well as highflow rates within the enclosure can be tolerated without risk of theseal for the arm blowing out. Yet there is still provided the advantageof a substantially frictionless pivoting action of the arm through thewall.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of thepreferred embodiment of this invention will be had by now referring tothe accompanying drawings, in which:

FIGURE 1 is a perspective view of the fiow responsive switch meansinserted in a fluid line;

FIGURE 2 is a cross section of the flow switch taken in the direction ofthe arrows 22 of FIGURE 1 showing the device prior to insertion in afluid line;

FIGURE 3 is a fragmentary cross section taken in the direction of thearrows 33 of FIGURE 2; and,

FIGURE 4 is a greatly enlarged cross section of the central portion ofFIGURE 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first toFIGURE 1 the flow switch includes a central frame structure providedwith a cover 11 and a lower portion 12 constituting an enclosure. Thisenclosure has inlet and outlet portions 13 and 14 for insertion in afluid line 15. As will become more fully evident as the descriptionproceeds, the interior of the structure under the cover 11 includes aswitch arranged to be actuated whenever the fluid flow rate through theline 15 drops below a predetermined value. Electrical output leads forthis switch are indicated at 16 and may be connected, for example, toapparatus to be shut down whenever the flow rate drops below suchpredetermined value. Alternatively, the leads 16 may connect to asuitable indicating means such as a light or buzzer to indicate a changein the flow rate from a desired value.

Referring now to FIGURE 2, the enclosure 12 of FIG- URE l defines ahollow interior 17 communicating with the inlet 13 and outlet 14. Anorifice means 18 is shown at the inlet area 13 and defines an orifice 19of given cross-sectional area. This orifice means 18 is removablysecured in the enclosure and includes an O-ring 20 for sealing purposesso that all fluid flow is directed through the orifice 19. The orificeitself may include an annular groove 21 for receiving a key or pin 22passed through a portion of the enclosure 12 to secure the orifice 18 inposition. A different orifice means may be substituted for the orifice18 by simply disassembling the device and removing the pin 22. Thesubstituted orifice means may have an orifice of either smaller orlarger cross-sectional area.

Extending into the enclosure 17 is the lower portion of an arm means 23.This lower portion serves to support a drag means in the form of a disc24 of given diameter. This disc is positioned with its plane normal tothe direction of fluid flow such as to intercept fluid flow from theorifice 19.

As shown in FIGURE 2, the arm means extends through a wall areaincorporating a sealing and pivoting means designated generally by thenumeral 25. The upper portion of the arm exterior of the enclosure 17 isindicated at 26. This portion of the arm connects to a biasing means inthe form of a spring 27. The free end of the spring connects to acarriage 28 which may be movably positioned along a track 29 as by ascrew 30. Access to the screw 30 may be had through a small opening 31in the cover 11. By this arrangement, the counterforce exerted by thespring 27 on the upper portion 26 of the arm may be adjusted by properthreading of the screw 30.

A suitable contacting area designated 32 on the upper portion of the arm26 opposite the point of connection of the spring 27 is positioned toengage a microswitch operating arm 33 extending from a microswitch 34.The leads 16 described in FIGURE 1 connect to the switch 34 as shown. InFIGURE 2, the area exterior to the enclosure is designated generally bythe numeral 35, this area accommodating the switch and spring structurenormally disposed beneath the cover 11.

FIGURE 3 illustrates the disc 24 in full plan View and it will be notedthat this disc has a given diameter D relative to the diameter d of theorifice 19 of FIGURE 2. For fairly small flow rates for example, fromfour to eight gallons per minute, the orifice diameter d will be lessthan the disc diameter D. For flow ranges for example from eight tosixteen gallons per minute, the orifice diameter d will approach thediameter D of the disc, and for large flow rates of the order fromsixteen to thirtytwo gallons per minute, the orifice diameter d will belarger than the disc diameter D. The force of the fluid impinging uponthe disc 24 will determine the deflection or physical movement of thelower portion of the arm 23 counter to the biasing of the spring 27connected to the upper portion. For a first given flow rate, the tensionexerted by the spring 27 may be adjusted to result in a deflection ofthe exterior portion 26 of the arm sufficient to actuate the switch forany value of flow rate within the first range. For a second range suchas described wherein a different sized orifice is substituted, therewill generally be no requirement for changing the spring 27, thedeflection being substantially the same but the dilference in the flowrate range being accommodated by the change in relative diametersbetween the orifice and the disc. Thus, the disc diameter D may be keptconstant throughout various flow ranges for the instrument it only beingnecessary to change the overall range by changing the orifice itself.Further, the geometry is such that a relatively wide range of flow ratescan be monitored.

The foregoing constitutes an important feature of the invention. Thus,the net effect of the change of the orifice diameter with flow raterelative to the disc diameter D is to maintain the range of forceapplied to the element 23 essentially constant for each flow range, i.e.the maximum and minimum force applied to element 23 over the flow ranges4-8 g.p.m., 8-16 g.p.m., 16-32 g.p.m., etc. is the same for all flowranges. Since the force range applied to element 23 is constant thebalancing spring force applied to 26 is likewise constant over thevarious flow ranges thus allowing one spring to function over a verywide total flow range. The unique feature of changing d while D is heldconstant is to reduce the effective area of the jet (formed by orifice19) intercepted by disc 24 as the flow rate increases thus limiting therange force applied to 24 as the flow increases.

FIGURE 4 illustrates in greatly enlarged view the area of the enclosurewall 12 through which the arm passes. As shown in FIGURE 4, this area isdefined by a bore 36 passing through the wall portion of the enclosuredefined by the frame 10. This bore has a relatively large entranceportion facing the enclosure interior 17. This entrance portiondecreases in diameter as indicated at 37 in FIGURE 4 to define a firstannular ledge 38 facing the interior 17 of the enclosure. The reduceddiameter portion 37 in turn is again decreased in diameter as indicatedat 39 to define a second annular ledge 40 also facing the interiorportion 17 of the enclosure. An annular resilient material 41 surroundsthe portion of the arm 23 passing through the bore structure andprovides a seal therefor. As shown, the upper portion adjacent to theexit end of the bore structure of this resilient material is engaged bythe second annular ledge 40. The lower portion of the resilient material41 in turn is engaged by a washer 42 arranged to press up against thematerial 41 as by means of suitable screws 43. Thus, the resilientmaterial 41 is sandwiched between the upper face of the washer 42 andthe second annular ledge 40.

A portion of the arm 23 passing through the bore struc ture includes atransverse opening 44 receiving a rigid transverse pin 45 passingthrough the resilient material 41. The extreme ends of the transversepin 45 extend beyond the resilient material 41 and engage or underliethe first annular ledge 38, this ledge defining suitable diametricallyopposite positioned shoulder means. The direction of the transverse pin45 is at right angles to the arm portion passing through the :borestructure and is also at right angles to the direction of fluid flow aswill be evident from FIGURES 2 and 3.

The rigid transverse pin 45 constitutes an extremely important featureof this invention in that it accomplishes two purposes: first, itdefines a pivot axis for rocking movement of the arm, the extreme endsof the pin itself simply rolling on the under shoulders defined by thefirst annular ledge 38; second, it positively prevents any blowing outof the resilient seal 41 and arm portion passing through the borestructure, the pin itself being blocked against translatory movementtowards the exterior 35 of the enclosure because of its passage throughthe opening 34 in the arm and its end extensions beneath the firstannular ledge.

Representative dimensions in fractions of an inch are given for thevarious bore diameters of the portions 36, 37, and 39. In addition,other representative dimensions in fractions of an inch or decimal partsthereof are shown for the thickness of the resilient material 41 anddiameter of the transverse pin 45.

OPERATION In operation, the flow responsive switch means is insertedinto a fluid line 15 by coupling the. line to the inlets 13 and 14. Withreference to FIGURE 2, it will be evident that fluid flow through theline 15 of FIGURE 1 will all be confined to pass through the orifice 19and some of the fluidflow will impinge on the face of the disc 24. Therewill thus be provided a force moment on the arm 23 tending to rock thesame in a counterclockwise direction as viewed in FIGURE 2. The exteriorportion 26 of the arm will thus engage the microswitch actuator 33 andclose the microswitch 34 so that, for example, if the switch is includedin a series power circuit to a piece of equipment, the equipment will beproperly energized.

Assume for the sake of illustrative purposes that it is desired toautomatically de-energize such equipment should the fluid flow rate dropbelow a given value. For this purpose, the tension exerted by the spring27 of FIGURE 2 is adjusted to have a value such as to overcome the dragforce exerted on the lower end of the arm 23 when the fluid flow ratedrops below the preselected value. Under these conditions, it will beevident that the microswitch 34 will remain closed provided that theflow rate is sufiicient to rock the arm and hold it in its rockedposition against the bias of the spring 27.

If the flow rate should drop below the selected value, the drag force onthe lower end of the arm 23 will decrease. permitting the spring 27 torock the arm in a clockwise direction and thus cause disengagement oftheupper portion of the arm with the microswitch actuator 33. Themicroswitch will thus open and automatically shut down the piece ofequipment to which it is connected.

' Alternatively, the microswitch may be a normally closed type switchwhich is held in open condition when the actuator 33 is engaged. In thisevent, when the flow rate drops below a predetermined value, the switch34 will close and could be employed to energize a suitable indicator. Instill another example, the switch 34 could be a normally open switch andconnected to a suitable indicator which would be energized upon closingof the switch. The spring 27 could be adjusted in tension such that thearm portion 32 would not engage the switch until the flow rate increasedbeyond a given desired maximum value, this maximum being sufficient toincrease the drag force to an extent that the microswitch actuator 33will be engaged. The device will then indicate increase of flow ratebeyond a desired value.

In all instance of operation, the switch may readily be accommodated todifferent flow ranges by simply substituting different sized orificesfor the orifice means 18 all as described heretofore with respect toFIGURE 2. It should again be emphasized that changes in flow rate rangescan be effected without having to substitute a spring of differentspring constant for the spring 27, the screw adjustment covering therange of each of the different ranges determined by the orifice size.

The actual rocking movement of the arm can be made fairly small byadjusting the proximity of the actuator 33 for the microswitch 34 to theupper portion 26 of the arm. Normally, the degree of rocking would notexceed four degrees. Over this rocking range, the annular sealing andpivoting structure 25 described in detail in FIGURE 4 operates extremelyefliciently to provide the desired sealing and pivoting action evenunder conditions of very high prssure in the enclosure compared to theexterior pressure. In other words, there is very little frictionalreistance afforded to the rocking movement when the range of rocking issmall.

As already described heretofore, the unique provision of the rigidtransverse pin in the bore hole structure as described in combinationwith the annular resilient material 41 assures that very little frictionwill result during pivoting movement and that the risk of blow out isminimal.

From the foregoing, it will be evident that the present invention hasprovided a greatly improved fluid flow responsive switch means whereinall of the various advantage, particularly the indepednece ofcalibration and sensitivity with time and enviroment, are fullyrealized.

What is claimed is:

1. A flow responsive switch means for insertion in a fluid flow linecomprising, in combination:

(a) a fluid enclosure having an inlet and outlet for insertion into saidflow line;

(b) orifice means at the inlet area of said enclosure defining anorifice of a first given cross-sectional area through which said fluidpasses;

(c) means in said enclosure responsive to a given change in flow rate offluid through said orifice for effecting a given physical movement insaid enclosure;

(d) a switch positioned exterior of said enclosure;

(e) arm means passing through a wall of said enclosure to the exteriorthereof in a direction substantially normal to the direction of fluidflow; and,

(f) sealing and pivoting means at the area of said wall through whichsaid arm means passes to permit rocking movement of said arm means, theportion of said arm means interior of said enclosure moving in responseto said given physical movement to thereby move the portion of said armmeans exterior of said enclosure, said switch means being positioned tobe actuated in response to movement of said portion of said arm meansexterior of said enclosure, said area of said wall being defined by abore of larger diameter than the portion of said arm means passingtherethrough, said bore defining on inner diametrical- 1y opposite wallportions, shoulder means, said sealing and pivoting means comprising:

(1) an annular resilient material filling the annulus defined betweenthe exterior of said portion of said arm means and inner wall of saidbore'to provide a fluid tight seal and yet permit said rocking movement;and,

(2) a rigid transverse pin passing through said resilient material andportion of said arm means in a direction at right angles to the axis ofsaid bore and the direction of said fluid flow, the ends of said pinextending beyond said resilient material to underlie said shoulder meansin said bore,

whereby said pin defines a pivot axis for said rocking movement, andwhereby said resilient sealing means is prevented by said pin from beingblown out of said bore when fluid pressure in said enclosure exceeds theexterior pressure.

2. A flow responsive switch means according to claim 1, in which saidfirst bore has a first given diameter at its entrance portion in thewall portion facing the interior of said enclosure, and thence decreasesto a second given diameter to define a first annular ledge facing saidentrance portion, diametrically opposite portions of said annular ledgedefining said shoulder means.

3. A flow responsive switch means according to claim 2, in which saidsecond given diameter decreases to a third given diameter at itsexterior exit portion to define a second annular ledge facing saidentrance portion, said resilient material underlying said second annularledge; and a washer member surrounding said arm means s'paced slightlyfrom said entrance portion and bearing against said resilient materialto sandwich the same between said washer and said second annular ledge.

4. A flow responsive switch means according to claim 1, includingadjustable biasing means connected to said arm means to exert a biasforce on said arm means opposing said physical movement whereby a givenforce on said arm means must be exerted as a result of fluid flow,

suflicient to overcome said bias force in order to move said portion ofsaid arm means exterior of said enclosure a suflicient distance toactuate said switch.

5. A flow responsive switch means according to claim 1, includingremovable means securing said orifice means in said enclosure such thatsaid orifice means may be removed and replaced with another orificemeans having an orifice of cross-sectional area diiferent from saidfirst cross-sectional area.

6. A flow responsive switch means according to claim 5, in which saidmeans in said enclosure responsive to a given change in flow rate offluid through said orifice 'for effecting said given physical movementconstitutes a disc secured to the interior portion of said arm means ina position with its plane normal to the direction of fluid flow tointercept said fluid flow, said disc having a fixed crosssectional areafor cooperation with different orifice means of smaller and largercross-sectional areas that may be inserted in said enclosure, wherebysaid orifice sizes may be smaller than said disc for monitoring lowrange flow rates, may approach. the size of said disc for medium rangeflow rates, and may be larger than said disc for high range flow ratesso that the range of forces applied to said disc is substantially thesame for each flow range.

References Cited UNITED STATES PATENTS 2,740,858 4/1956 Euler 200-8l.93,119,979 1/ 1964 Martin 2008l.9 XR 3,126,463 3/1964 Kmiecik 200-8l.93,260,815 7/1966 Trimmer 20081.9 3,291,495 12/1966 Liebig 277174 XR3,364,454 1/1968 Froebe 277l74 XR 3,369,089 2/ 1968 Hellman ZOO-81.9

ROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant ExaminerU.S. Cl. X.R. 277-174

